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Sakamoto H, Inutsuka A. Membrane-Targeted palGFP Predominantly Localizes to the Plasma Membrane but not to Neurosecretory Vesicle Membranes in Rat Oxytocin Neurons. Acta Histochem Cytochem 2024; 57:85-88. [PMID: 38695035 PMCID: PMC11058463 DOI: 10.1267/ahc.24-00001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/04/2024] [Accepted: 01/22/2024] [Indexed: 05/04/2024] Open
Abstract
Recent advances in viral vector technology, specifically using adeno-associated virus (AAV) vectors, have significantly expanded possibilities in neuronal tracing. We have utilized the Cre/loxP system in combination with AAV techniques in rats to explore the subcellular localization of palmitoylation signal-tagged GFP (palGFP) in oxytocin-producing neurosecretory neurons. A distinctive branching pattern of single axons was observed at the level of the terminals in the posterior pituitary. Despite challenges in detecting palGFP signals by fluorescent microscopy, immunoelectron microscopy demonstrated predominant localization on the plasma membrane, with a minor presence on the neurosecretory vesicle membrane. These findings suggest that membrane-anchored palGFP may undergo exocytosis, translocating from the plasma membrane to the neurosecretory vesicle membrane. In this study, we observed characteristic axon terminal structures in the posterior pituitary of oxytocin neurons. This study indicates the importance of understanding the plasma membrane-specific sorting system in neuronal membrane migration and encourages future studies on the underlying mechanisms.
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Affiliation(s)
- Hirotaka Sakamoto
- Department of Biology, Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, Japan
- Ushimado Marine Institute (UMI), Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Okayama, Japan
| | - Ayumu Inutsuka
- Division of Brain and Neurophysiology, Department of Physiology, Jichi Medical University, Tochigi, Japan
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Nishikage S, Fujisawa A, Endoh H, Sakamoto H, Suzuki T, Kanzawa M, Ishii S, Okano M, Nitta E, Yakushijin K, Asakura H, Nozu K, Nitta R, Katayama Y, Sakaguchi K. Amyloid deposition through endocytosis in vascular endothelial cells. Exp Hematol 2024; 129:104129. [PMID: 37952890 DOI: 10.1016/j.exphem.2023.11.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/06/2023] [Revised: 11/02/2023] [Accepted: 11/04/2023] [Indexed: 11/14/2023]
Abstract
No mechanistic lead is known for establishing AL amyloid deposits in organs. We here report an electron microscopic (EM) analysis in a case of intestinal AL amyloidosis before initiating treatment for amyloidosis. The dense deposits of amyloid fibrils are concentrated around the small blood vessels in the submucosal area of intestinal tissue. Surprisingly, we observed endothelial cells (ECs) of blood vessels containing plenty of endocytotic (pinocytotic) and transcytotic vesicles at the luminal side and above the basement membrane, indicating the one-way active trafficking of either the immunoglobulin (Ig) light chain or preassembled amyloid fibrils from the luminal side of ECs to the extraluminal area of ECs. Immunoelectron microscopy displayed that the immuno-gold signals were observed in the vascular cavity and the subendothelial area of amyloid deposits. However, there is no sign of an Ig light chain in pinocytotic vesicles. Therefore, the intestinal ECs may actively pump out mainly the preassembled amyloid fibrils (not light chains) from the blood stream into the subendothelial area as a physiologic function.
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Affiliation(s)
- Seiji Nishikage
- Division of General Internal Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Akira Fujisawa
- Division of General Internal Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Hiromi Endoh
- Division of Structural Medicine and Anatomy, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Hirotaka Sakamoto
- Department of Biology, Faculty of Environmental, Life, Natural Science and Technology, Okayama University, Kita-ku, Okayama, Japan
| | - Tomohide Suzuki
- Division of Hematology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Maki Kanzawa
- Division of Diagnostic Pathology, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Shinichi Ishii
- Division of Hematology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Mitsumasa Okano
- Division of General Internal Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Eriko Nitta
- Division of Structural Medicine and Anatomy, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Kimikazu Yakushijin
- Division of Oncology/Hematology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Hidesaku Asakura
- Department of Hematology, Kanazawa University Hospital, Kanazawa, Japan
| | - Kandai Nozu
- Department of Pediatrics, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Ryo Nitta
- Division of Structural Medicine and Anatomy, Department of Physiology and Cell Biology, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan
| | - Yoshio Katayama
- Division of Hematology, Department of Internal Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan.
| | - Kazuhiko Sakaguchi
- Division of General Internal Medicine, Department of Internal Medicine, Kobe University Graduate School of Medicine, Chuo-ku, Kobe, Japan.
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McKenzie AT, Nnadi O, Slagell KD, Thorn EL, Farrell K, Crary JF. Fluid preservation in brain banking: a review. FREE NEUROPATHOLOGY 2024; 5:5-10. [PMID: 38690035 PMCID: PMC11058410 DOI: 10.17879/freeneuropathology-2024-5373] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Subscribe] [Scholar Register] [Received: 02/12/2024] [Accepted: 03/29/2024] [Indexed: 05/02/2024]
Abstract
Fluid preservation is nearly universally used in brain banking to store fixed tissue specimens for future research applications. However, the effects of long-term immersion on neural circuitry and biomolecules are not well characterized. As a result, there is a need to synthesize studies investigating fluid preservation of brain tissue. We searched PubMed and other databases to identify studies measuring the effects of fluid preservation in nervous system tissue. We categorized studies based on the fluid preservative used: formaldehyde solutions, buffer solutions, alcohol solutions, storage after tissue clearing, and cryoprotectant solutions. We identified 91 studies containing 197 independent observations of the effects of long-term storage on cellular morphology. Most studies did not report any significant alterations due to long-term storage. When present, the most frequent alteration was decreased antigenicity, commonly attributed to progressive crosslinking by aldehydes that renders biomolecules increasingly inaccessible over time. To build a mechanistic understanding, we discuss biochemical aspects of long-term fluid preservation. A subset of lipids appears to be chemical altered or extracted over time due to incomplete retention in the crosslinked gel. Alternative storage fluids mitigate the problem of antigen masking but have not been extensively characterized and may have other downsides. We also compare fluid preservation to cryopreservation, paraffin embedding, and resin embedding. Overall, existing evidence suggests that fluid preservation provides maintenance of neural architecture for decades, including precise structural details. However, to avoid the well-established problem of overfixation caused by storage in high concentration formaldehyde solutions, fluid preservation procedures can use an initial fixation step followed by an alternative long-term storage fluid. Further research is warranted on optimizing protocols and characterizing the generalizability of the storage artifacts that have been identified.
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Affiliation(s)
| | - Oge Nnadi
- Brain Preservation Foundation, Ashburn, Virginia, USA
| | - Kat D. Slagell
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Friedman Brain Institute, Departments of Pathology, Neuroscience, and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Emma L. Thorn
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Friedman Brain Institute, Departments of Pathology, Neuroscience, and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - Kurt Farrell
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Friedman Brain Institute, Departments of Pathology, Neuroscience, and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, USA
| | - John F. Crary
- Department of Neuroscience, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Friedman Brain Institute, Departments of Pathology, Neuroscience, and Artificial Intelligence & Human Health, Icahn School of Medicine at Mount Sinai, New York, New York, USA
- Neuropathology Brain Bank & Research Core and Ronald M. Loeb Center for Alzheimer's Disease, Icahn School of Medicine at Mount Sinai, New York, New York, USA
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